Highly fluorinated polyurethanes

ABSTRACT

Polyurethanes having the repeating unit:   WHERE N IS AN INTEGER OF 1 TO 12, P IS AN INTEGER OF 2 TO 23, Y IS AN INTEGER OF 1 TO 1000, AND R is any radical suitable to link isocyanate groups and is preferably selected from the group consisting of alkylene and halogen substituted alkylene radicals of four to 12 C atoms, substituted and unsubstituted phenylene groups of up to 20 C atoms.

United States Patent [191 Fietcher et al.

[ Aug. 28, 1973 HIGHLY FLUORINATED POLYURETHANES [76] Inventors: James C. Fletcher, Administrator of the National Aeronautics and Space Administration with respect to an Invention of; Eugene C. Stump, Gainesville, Fla.; Stephen Eugene Rochow, Ann Arbor, Mich.

[22] Filed: Apr. 4, 1972 [21] Appl. No.: 241,061

Related US. Application Data [63] Continuation-impart of Ser. No. 770,417, Oct. 24,

1968, abandoned.

[52] US. Cl. 260/77.5 AP [51] Int. Cl C083 22/14 [58] Field of Search 260/776 AP [56] References Cited UNITED STATES PATENTS 3,574,770 4/197] Paine 260/775 AP Primary ExaminerDonald E. Czaja Assistant Examiner-M. J. Welsh Attorney-John R. Manning. Monte F. Mott and Wilfred Grifka [57] ABSTRACT Polyurethanes having the repeating unit:

I 1| 3 LCH;[CF(GFa)O(CFz) 0CF(CFaHnCHzOCNHRNHCOJ where 7 Claims, No Drawings HIGHLY FLUORINATED POLYURETHANES CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of U.S. application Ser. No. 770,417 filed Oct. 24, 1968, now abandoned.

ORIGIN OF THE INVENTION The invention described herein was made in the performance of work under a NASA contract and is sub ject to the provisions of Section 305 of the National Aeronautics and Space Act of 1958, Public Law 83-568 (72 Stat. 435; 42 USC 2457).

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention is in the field of polymers. More particularly, the invention relates to new highly fluorinated polyurethane polymers.

2. Description of the Prior Art Polyurethane resins, also known as isocyanate resins, are a well known class of synthetic polymers. They may be either thermoplastic or thermosetting. The polyurethane resins are made into flexible or rigid foams and flexible and stiff fibers. They are also utilized as coatings, linings, and as elastomers. The polymer units are formed from the reaction of a diisocyanate with a diol. Polyethers have been the most important source of hydroxyl groups. One of the most popular polyethers utilized is polyoxypropylene. Toluene diisocyanate and diphenylmethane-4,4diisocyanate are two of the more prevalent diisocyanates reacted to form the polyurethane resins.

In the herein invention, a perfluorinated hydroxy terminated polyether having the general formula where n is an integer of l to l2, and p is an integer of 2 to 23 is reacted with a diisocyanate to form the polyurethane. In U.S. Pat. No. 3,250,807, there is disclosed the basic monomeric ether structure utilized. However, the patent discloses the ether terminated with acid or acid fluoride groupings rather than hydroxyl groupings. In. U. S. Pat. No. 3,637,842 of Jan. 25, 1972, there is disclosed a method of polymerizing the ethers disclosed in the aforementioned patent such that n is equal to at least 2 to l2. Additionally, the copending application further discloses converting the acid fluoride terminated polyethers to hydroxy terminated ones. It is these hydroxy terminated perfluoropolyethers that are contemplated as the starting materials utilized herein. Though, as indicated, there are several polyurethane resins available on the commercial market, none would possess the same thermal properties, non-flammability and the like, of polyurethanes using perfluorinated ethers.

OBJECTS OF THE INVENTION An object of this invention is to provide new polyurethane resins having improved oxidative stability.

Another object of this invention is to provide new polyurethane resins having outstanding chemical resistance and low temperature flexibility.

A further object of this invention is to provide highly fluorinated polyurethanes.

Other objects will be apparent from the following detailed description and examples.

BRIEF SUMMARY OF THE INVENTION where n is an integer of l to 12, p is an integer of 2 to 23, y is an integer of l to I000, and R is any radical suitable to link isocyanate groups and is preferably selected from the group consisting of alkylene and halogen substituted alkylene radicals of four to 12 C atoms, substituted and unsubstituted phenylene groups of up to 20 C atoms. The polyurethane results from the reaction of a diol having the formula HOCH [CF(CF )O(CF OCF(CF )],,CH OI-I, where p and n are as defined above, with a suitable diisocyanate such as tetrafluorom-phenylene diisocyanate. The formation of the final polyurethane product merely involves heating the two reactants over a wide temperature range for varying lengths of time to obtain products having different properties of hardness, strength and the like. The resultant polyurethanes can be used for films, sheets, seals, and many other applications where good chemical resistance, low temperature flexibility and non-flammability is desired. It is believed the invention will be further understood from the following detailed description and examples.

DESCRIPTION OF PREFERRED EMBODIMENTS As indicated, the starting diol prepolymer material utilized to form the polyurethanes of this invention having the general formula n is an integer of 1 to 12, p is an integer of 2 to 23, y is an integer of l to 1000, and R is any radical suitable to link isocyanate groups and is preferably selected from the group consisting of alkylene and halogen substituted alkylene radicals of four to 12 C atoms, substituted and unsubstituted phenylene groups of up to 20 C atoms, is disclosed in the above-mentioned U.S. Pat. No. 3,637,842. Briefly, these diols are derived from an acid fluoride terminated corresponding perfluoroether which has first been polymerized and then reduced to change the terminal groups from acid fluoride to hydroxyl. As indicated in the co-pending application, it is preferable that the diols have a molecular weight range of about 1500 to 2000 to provide ease of handling and to produce satisfactory end products. The diisocyanate utilized has the general formula: OCNRNCO where R is as defined in the above general formula for products of this invention. The halogen substitutions are generally either chlorine or fluorine atoms. The substituted phenylene groups include halogen substitutions, alkyl, aryl and alkaryl groups. To practice this invention, any diisocyanate previously and conventionally utilized to produce polyurethane resins is contemplated. Examples of conventional diisocyathe good thermal, oxidative, and chemical resistance properties of other known highly fluorinated materials such as Teflon, which is tetrafluorethylene, yet are elastomeric materials and can be utilized as expulsion bladnates include toluene diisocyanate, including mixtures 5 der materials, seals, gaskets, coatings and other similar of its isomers such as the 2,4 and 2,6 isomer, diapplication. phenylmethane-4, 4'-diisocyanate and hexamethylene It is believed the invention will be better understood diisocyanate. from the following detailed examples:

Particularly, it is desirable in the herein invention to utilize diisocyanates containing a maximum amount of EXAMPLE 1 fluorine atoms. The extremely good chemical resistance, non-flammability and the like can be attribut- A hydroxy terminated perfluoro polyether having the able to the presence of fluorine atoms in the polymer f rmula HOCH [CF(CF )O(CF OCF(CF )],,CH OH chain. This, if the diisocyanate also contains a high subnd p epared in ac r Wit th m t d d r d in stitution of fluorine atoms like the diol utilized, one obthe above mentioned 3,637,842 was tains a polymer containing the desired content of fluoliz d. This prepolymer had a molecular weight of about rine. Thus, it is preferred to utilize diisocyanates such 1500. 10.5 grams or .0068 moles of the polyether was as tetrafluoro-m-phenylene diisocyanate, tetrafluoro-padded together with 2.35 grams or .0101 mole of phenylene diisocyanate, and the like. tetrafluoro-m-phenylene diisocyanate to a 100 ml. The resultant polymers of this invention will range resin kettle equipped with a stirrer, N inlet and outlet. from sticky semi-solids to tough brittle sheets, depend- The diisocyanate was previously prepared in accord ing upon the amount of diisocyanate utilized in the exwith the procedure set forth by R. Gosnell and 1. H01- tension and cross linking reaction that transpires belander in the Journal of Macromolecular Science tween it and the diols. It should be noted that although (Physics) 81(4), 831 (1967). After 20 minutes of stirthe hardness of the resultant polymers increases with ring at room temperature, the reactants had balled increasing ratio of diisocyanate to diol, the glass tern about the stirrer. The material was then removed and perature of the resultant polyurethanes is not adversely placed in a press between 10 mil shims at 3000 psi and affected. Thus, it is contemplated to utilize amole ratio 160C for 16 hour. This produced a yellow, flexible of diisocyanate to diol of from 1:1 up to about 3: 1. The sheet of the resultant polymer. The glass transition tempreferred mole ratio range of the diisocyanate to diol perature was 80C and the Shore A hardness was 79. is between 1:1 and 2:1. The above was repeated varying the amounts of rare The time and temperature of the polymerization repolymer and diisocyanates as well as the temperature action is dependent upon the molecular weight of the and time of heating. Hydroxy terminated per prepolymer and the type ofdiisocyanate used. Complefluoropolyether prepolymer of varying molecular tion of the polymerization for the given diol and diisoweights ranging from 1500 to 2193 was utilized. The cyanate can be determined by the increase in viscosity results of the various preparations indicating the glass of the melt polymer. Generally, the temperature of curtransition temperature Tg and the Shore A hardness, ing can vary from 25 to 100C, while the time of the together with an indication as to the type of product, cure can range from 10 to 30 minutes. are indicated in the following table:

TABLE 1 Polyurethanes from HOCHz[CF(CF )0(CFz)50CF(CF3)]nCHzOH and Tetrafluorom-phenylene Diisocyanate Mole ratio Glass Pre- Grams Grams diisotemper prediisoeyanate/ Temp, Time ature Hardpolymer cyanate prepolymer 0 (min) 'Ig C.) ness Remarks 10.63 2.24 2/1 150 90 -73 Brown, flexible film.

11.7 1.24 1 1 140 180 Sticky, semi-solid. 10.6 3.43 3/1 140 120 Weak. elastomeric film. 11.35 4.17 2.38/1 -70 Brittle, yellow, slightly flexible sheet.

9.90 1. 82 1. 2/1 -80 Weak, elastomeric solid. 10.1 1.56 1/1 39 30 Yellow, elastomerio film, decomposes at 23$. 9. 05 2. 10 1. 5/1 25-30 10 Yellow, elastorneric sheet. 11. 25 2. 09 1. 2 1 25-30 -16 62 Do. 10.15 2.35 1. 5 1 25-30 20 so 79 Yellomfiexible sheet.

10.0 3. 09 2/1 25-30 10 79 90 Yellow slightly flexible sheet.

b By differential scanning calorimeter. h Shore A.

It can be appreciated that the end groups of the polymers of this invention are not readily determined. The polymers can be hydroxy or isocyanate terminations,

depending upon the stoichiometry of the reaction, re-

Though the materials prepared in the foregoing table were all pressed to form sheets of the polymer of this invention, it should be understood that the material can be formed into various other shapes such as seals, hoses and various forms of coatings.

What is claimed is:

l. Polyurethanes having the repeating unit:

where n is an integer of 1 to 12,

p is an integer of 2 to 23,

y is an integer of l to I000, and

R is any radical suitable for linking isocyanate groups.

2. The polyurethane of claim 1 where R is selected 5 4. The polyurethane of claim 3 where the mole ratio of diisocyanate to diol is from lzl to 2:].

5. The polyurethane of claim 3 where the diisocyanate has the general formula:

OCNRNCO, where R is selected from the group consisting of alkylene and halogen substituted alkylene groups of four to 12 C atoms, substituted and unsubstituted phenylene groups of up to 20 C atoms.

6. The polyurethane of claim 3 wherein the diisocyanate is selected from the class consisting of tetrafluorom-phenylene diisocyanate and tetrafluoro-p-phenylene diisocyanate.

7. The polyurethane of claim 3, where p 5. 

2. The polyurethane of claim 1 where R is selected from the group consisting of alkylene and halogen substituted alkylene groups of four to 12 C atoms, substituted and unsubstituted phenylene groups of up to 20 C atoms.
 3. A polyurethane formed from the reaction at a 1:1 to 3:1 mole ratio of a diisocyanate with a diol having the formula: HOCH2(CF(CF3)O(CF2)pOCF(CF3))nCH2OH where n is from 1 to 12 and p is from 2 to
 23. 4. The polyurethane of claim 3 where the mole ratio of diisocyanate to diol is from 1:1 to 2:1.
 5. The polyurethane of claim 3 where the diisocyanate has the general formula: OCNRNCO, where R is selected from the group consisting of alkylene and halogen substituted alkylene groups of four to 12 C atoms, substituted and unsubstituted phenylene groups of up to 20 C atoms.
 6. The polyurethane of claim 3 wherein the diisocyanate is selected from the class consisting of tetrafluoro-m-phenylene diisocyanate and tetrafluoro-p-phenylene diisocyanate.
 7. The polyurethane of claim 3, where p
 5. 